650 CRANIAL NERVES. [BOOK m. 



10. Pneumogastric. Vagus. 



Efferent Fibres. Motor nerve for the muscles of the pharynx, 

 for the movements of the oesophagus, of the stomach, of the 

 intestines, for the muscles of the larynx, possibly for the plain 

 muscular fibres of the trachea and bronchial divisions. Vaso- 

 motor fibres for lungs. Inhibitory nerve of the heart. Trophic 

 fibres for lungs and heart. 



Afferent Fibres. Sensory nerve of the respiratory passages, 

 and of the pharynx, oesophagus and stomach. Afferent nerve, 

 augmenting and inhibiting, of the respiratory centre, afferent 

 inhibitory nerve (depressor branch) of the medullary vaso-motor 

 centre, afferent nerve producing salivary secretion, inhibiting 



rcreatic secretion. It is stated that in the rabbit the vagus may 

 easily dissected into two strands, an outer one containing the 

 afferent, and an inner one containing the efferent fibres. 



11. Spinal accessory. Motor nerve to the sterno-mastoid and 

 trapezius muscles. It receives recurrent sensory fibres from the 

 cervical nerves. Part of the spinal accessory blends with the 

 pneumogastric, and the efferent effects (such as the movements of 

 the larynx, pharynx, &c., and cardiac inhibition) of the united 

 trunk seem to be largely due to the spinal accessory fibres con- 

 tained in them. It is stated however that division of the spinal 

 accessory before it joins the pneumogastric, does not entirely do 

 away with either swallowing or the movements of the larynx. In 

 the movements of the oesophagus and stomach, brought about by 

 the vagus acting as an efferent nerve, the accessory fibres seem to 

 have no share. The cardiac inhibitory fibres seem to be distinctly 

 of accessory origin. 



12. Hypoglossal. Motor nerve for the muscles of the tongue, 

 and for all the muscles connected with the hyoid bone except the 

 digastric, stylo-hyoid, mylo-hyoid, and middle constrictor of the 

 pharynx ; it also supplies the sterno-thyroid. It receives sensory 

 fibres from the fifth and vagus, and is also connected with the 

 three upper cervical nerves as well as with the sympathetic. 



